The present invention relates to nanolaminated structures, particularly to flat, polished surfaces of nanolaminate composites to enhance the detection of dilute analyte particles in water, and more particularly flat, polished surfaces of nanolaminates having trenches and/or baffles selectively etched therein to increase the amount of exposed conductive materials in the flat surfaces or to screen the conductive materials from analytes of larger sizes, thereby increasing the sensitivity or selectivity of detection devices.
Electrophoretic and electrochemical devices have been proposed that employ flat, polished, exposed surfaces of nanolaminate composites to enhance the detection of dilute analyte particles. The nanolaminate composites were formed by magnetron sputtering of alternating layers of a conductive material and an insulative material, such as silica and alumina, whereafter the composites were cut and polished to expose a nanolaminate surface as a sensor. These prior nanolaminate composites or structures are exemplified by the sensor template described and claimed in copending U.S. application Ser. No. 10/167,926, filed Jun. 11, 2002.
The present invention is an improvement of the prior nanolaminate approach and comprises the formation of trenches and baffles in the flat exposed surface of the nanolaminate, the formation of such trenches and baffles being carried out by selective etching, whereby greater exposed conductive surfaces are produced in the nanolaminate, or the conductive surfaces are recessed and screened by insulating baffles.
It is an object of the present invention to provide improved microlaminated composites for detection of dilute analyte particles.
A further object of the invention is to provide microlaminate composites with trenches and baffles for increasing exposed surface area of the composites, or for screening the relevant surfaces.
A further object of the invention is to provide selectively-etched nanochannels for electrophoretic and electrochemical devices.
Another object of the invention is to increase the sensitivity of electrochemical detection devices to low concentration of analyte.
Another object of the invention is to increase the amount of exposed metal in nanolaminate composites to facilitate electrochemical redox reaction or to control the exposure of the metal surfaces to analyte of large size, and allow additional discrimination of colloidal particles during cyclic voltammetry.
Another object of the invention is to improve the plug flow characteristic of a fluid channel incorporating nanolaminate surfaces.
Another object of the invention is to provide flat, exposed striped surfaces of nanolaminate composites with selectively-etched trenches and baffles that provide size selectivity in performing electrochemical redox reactions.
Other objects and advantages of the invention will become apparent from the following description and accompanying drawings. Basically, the invention involves selectively-etched nanolaminate composites or structures for electrophoretic and electrochemical devices. For example, the selectively-etched nanolaminates may be composed of alternating layers of a metal and an insulator, cut to expose the metal and insulator on a preferably flat surface. The metal and/or the insulator layers may be etched such that the exposed surfaces protrude into the fluid channel by controlled amounts. The selectively-etching may result, for example, in baffle of protruding layers, the metallic layers having been partially etched away. Also, the nanolaminates can be etched to form trenches or fluid flow channels therein. In addition, the selective-etching may result in a baffle of protruding layers located between two etched channels. A series of etched nanolaminates may be positioned along a fluid flow channel to function a successive filtration states as the fluid flows through the channel, which is accomplished by a series of etched baffles or trenches which function as individual sieves for different size particles. Also, etched channels in one nanolaminate may be combined with a second etched nanolaminate to enable size-selected cyclic voltammetry between the electrodes or exposed metal strips or layer sections of each nanolaminate.
The selectively-etched nanolaminate composites or structures may be incorporated into any microfluidic device for the purpose of processing, separating, or performing a chemical or biological assay or analysis on a very small fluid sample. Such devices can be used as detectors of pathogens or other trace analytes.